Why does my sister get everything she wants, while I get yelled at?

This may be very complicated. It is important for you to know that it is not your fault nor is it fair. Seeking support with this situation that is in no way your fault is a brave step and you are on the right track. the cycle of abuse takes on many patterns. Developing a broad support network to help you cope is an important step. Remember to breath. Also developing a yoga and meditation practice can be helpful in managing the stressful emotions that arise from experiences that hit deep in the psyche such as family issue like this one. You have done great for yourself today I’m seeking out support!

This is a tough one to answer without knowing more about your unique situation. Parenting is hard - and being a child of any age is equally hard. Sometimes, parents connect with one child better than others, or recognise themselves in one of their children more- and both of these things can backfire. Recognising similarities and differences can go both ways - either the parent will enjoy trying to bond in the ways they like, or they will be uncomfortable, and, at times, even reactive to those similarities or differences - even subconsciously. Another can be expectations- I have seen parents who had very low expectations of good behaviour from one child, and who offered every form of bribe they could think of to try and elicit the behaviours they wanted from them, including heaping praise upon every little achievement, while they almost constantly ignored or berated another child, who was much less trouble behaviour wise, but because of that, the expectations of 'good behaviour' were much higher for them. It can be a myriad of reasons, and often can be exacerbated by a lack of awareness, and sometimes, a skill gap in parenting.